Pin-Hole leaks in Carbon Steel
Pin-Hole leaks in Carbon Steel
(OP)
We just found multiple pin hole leaks in Carbon Steel tubing in our HVAC unit. The tubes carry 50# of steam (might have trace amounts of cyclohexlamine and hydrazine (.1-.2 ppm) at ~300 F. Aluminum fins are touching (not actually attached) the steel and most (if not all) of the pinholes are located beneath the aluminum fins. I'm concerned about galvanic corrosion but don't think it could be that since the Aluminum is the more active metal. Could erosion-corrosion cause these pinholes? Maybe it's just localized corrosion? Finally, could galvanic corrosion occur at this location? Any information would help! Thanks!





RE: Pin-Hole leaks in Carbon Steel
Thanks
SeasonLee
RE: Pin-Hole leaks in Carbon Steel
Have you determine which side of the tube the leak originated from?
One reason for asking that I've seen Al fins wear small holes in thin wall CS tubes due to vibration of the fins.
RE: Pin-Hole leaks in Carbon Steel
I've found the article below interesting even if the materila of tubes is Cu and not Carbon Steel but it describes a type of corrosion similar to your case:
"In most failures of indoor coils, however, the
copper tubes will have been penetrated while there
will be little corrosion on the aluminum fins in direct
contact. Figure 2 shows pits in the copper tube
surface and the contacting aluminum fin surfaces. In
these cases the corrosion appears to be caused by a
direct attack of the corroding agent on the copper in
spite of the presence of the 'more sacrificial'
aluminum."
CORROSION OF ALUMINUM-FIN, COPPER-TUBE HEAT EXCHANGE COILS
https://
hope this can help u
Regards
S.
Corrosion Prevention & Corrosion Control
RE: Pin-Hole leaks in Carbon Steel
RE: Pin-Hole leaks in Carbon Steel
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Plymouth Tube
RE: Pin-Hole leaks in Carbon Steel
RE: Pin-Hole leaks in Carbon Steel
RE: Pin-Hole leaks in Carbon Steel
RE: Pin-Hole leaks in Carbon Steel